plural vs long johns

plural and long johns both are nouns.

Word	Noun	Adjective	Verb	Adverb
plural	Yes	Yes	No	No
long johns	Yes	No	No	No

plural (noun)	long johns (noun)
the form of a word that is used to denote more than one	warm underwear with long legs

plural (adjective)	long johns (adjective)
grammatical number category referring to two or more items or units
composed of more than one member, set, or kind